Field of the Invention
The present invention relates to a lens barrel and an optical apparatus including the same.
Description of the Related Art
In a so-called inner focus lens barrel (also referred to as a rear focus lens barrel), a change of a focal length in zooming causes a focal plane to move, which is called a focus variation. In order to reduce the focus variation, it is well known to provide a cam barrel driven in a magnification-varying operation (that is, in zooming) with a nonlinear focus cam that is used to continuously change a moving range of a focus lens unit from an infinite end to a short-distance end in an optical axis direction in accordance with the change of the focal length.
Japanese Patent Laid-open No. (“JP”) 2006-54543 discloses a lens barrel including a plurality of cams rotatable about an optical axis in focusing so as to move a plurality of lens units in an optical axis direction. At least one of the cams is a range varying cam that changes the moving ranges of the lens units in accordance with a magnification state.
However, in the invention disclosed in JP 2006-54543, a first focus lens unit is held by a focusing cam barrel and a rotating barrel, and a second focus lens unit is held by the focusing cam barrel or a magnification-varying cam barrel, and the rotating barrel. In other words, a plurality of focus lens units are held by the rotating barrel with two different components. Any position shift between the two different components changes positions of the focus units, resulting in low accuracy of holding the focus units in some cases.